Do you have a 1959 Truck Shop Manual?
In 1960, the PVC hose on a 261 ran from the carburetor air cleaner to the left rear of the valve cover.
The 1959 valve cover might have had the oil filler in the middle of the valve cover.
A non-vented oil filler cap would have been used with a PCV system.
A member has designed an after-market PVC set-up for 235/261 engines. Maybe he will post info, or someone will post a link to his web site (that has detailed instructions)?
